Steerable Landing Gear Slip-Reduction Control
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Solution Overview
Problem
Existing aircraft control systems fail to effectively reduce undesirable vibrations during taxiing operations, particularly when using steerable landing gear, which can affect operational efficiency and passenger comfort.
Innovation Solution
A slip-reduction control unit that adjusts the rate of change of the steerable landing gear's angle based on aircraft motion, steering angle, and slip parameters to minimize vibrations without compromising maneuverability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the steering angle of the landing gear is increased to improve maneuverability, then the aircraft can turn more effectively, but vibration increases
Solution Approach 1:
The patent implements dynamic control of the steering angle rate based on real-time aircraft speed. The control system continuously adjusts the maximum allowable rate of change of the steering angle according to the current speed regime, allowing aggressive steering at low speeds for good maneuverability while limiting steering rate at high speeds to reduce vibration and tire slip.
Solution Approach 2:
The system changes the parameter of steering angle rate limit based on aircraft speed. Different speed thresholds correspond to different maximum steering angle rates, optimizing the balance between maneuverability and vibration reduction across the entire operating range of the aircraft.
2Loss of time
If the rate of change of steering angle is increased to improve response time, then the aircraft responds faster to pilot input, but tire wear increases
Solution Approach 1:
The control system dynamically adjusts the steering angle rate based on aircraft speed. At low speeds where tire slip is less problematic, the system allows higher steering angle rates for fast response. At higher speeds, the system reduces the steering angle rate to minimize tire slip and wear, while still providing adequate response time.
Solution Approach 2:
The maximum steering angle rate parameter is changed according to speed conditions. The control system selects from multiple predefined rate limits based on the current speed regime, optimizing the trade-off between response time and tire wear across different operating conditions.
3Object-affected harmful factors
If automatic control is implemented to reduce vibration, then passenger comfort improves, but system complexity increases
Solution Approach 1:
The control system uses feedback from the aircraft speed signal to automatically adjust the steering angle rate limit. The control unit continuously monitors the current steering angle demand and compares it against the speed-dependent maximum allowable rate, automatically enforcing the appropriate limit without requiring additional sensors or complex algorithms.
Solution Approach 2:
The system uses existing aircraft systems (speed sensors, steering angle sensors already present for normal operation) to provide the vibration reduction function. No additional sensors or complex external systems are required - the control unit leverages available data to automatically optimize steering behavior.
Data Source
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AI summary
A slip-reduction control unit is employed on an aircraft (2; 102) having a longitudinal axis (6) and a steerable landing gear, for example a nose landing gear (8; 108) wheel (NLG). The control unit (130) is arranged to receive steering input signals from which a target steering command output may be ascertained. The control unit is arranged to receive one or more additional input signals (140; 150; 190) concerning at least one of (a) the motion of the aircraft, (b) a steering angle, and (c) a parameter relating to the slip sustained by the steerable landing gear. The slip-reduction control unit (130; 133) is arranged so that, in dependence on at least the additional input signals (140; 150; 190), the rate of change of the angle (θNLG) of the one or more steerable wheels (12) that would otherwise be commanded is reduced. Vibration on the aircraft (2; 102) that might otherwise be caused by such steering may be reduced by so controlling the rate of change of the steering angle.